To clean, use hot soapy water and rinse thoroughly with hot water.
For tough cleaning jobs, add 1/4 cup of baking soda to 3/4 water and shake for 30 seconds. Add 1/4 cup of lemon juice, shake for 10 seconds and vent holding away from face. Repeat 3 times. Expel as much air as possible then leave for 20 minutes. Rinse with hot water. Warning: Adding lemon juice to baking soda makes it fizz so don't leave your bladder unattended for too long.
Only used once so far, but easy to refill, not too heavy to carry around with 2.5 Lts.
Seems to be very well made, handy having the hose in two parts to make threading it through the back pack very easy also when refilling the bag